Adjustable ceiling mounted filter access frame and return system

ABSTRACT

An above-ceiling system for conditioning air in a structure. The system comprises a plurality of return ducts into the inlet of the air handler, the return ducts carrying air from substantially all of the major spaces within the structure. A filter housing and filter disposed above the ceiling with an opening through the ceiling into the space below, having a cover disposed below the ceiling secured by fasteners and providing access from the space below the ceiling for removal and replacement of the filter.

This application claims priority from a provisional application, “Ceiling Mounted Filter Access Frame and Return System”, Ser. No. 60/547,236, filed Feb. 23, 2004.

FIELD OF THE INVENTION

The present invention relates to the field of heating and air conditioning equipment, and particularly to in-ceiling mounted units.

BACKGROUND OF THE INVENTION

Forced air central heating and cooling systems “condition” (that is, heat or cool, humidify or dehumidify) the air in a structure through air by pushing air through a central air supplier (air handler). The air is routed through air ducts to the various rooms of the structure, then is returned to the air handler through air return ducts. The air is reheated/recooled and it circulates through the system continuously to maintain a comfortable environment within the structure.

Because this is a “forced” air system, and the structure is normally closed, the forced air can cause air pressure differences between rooms in the structure. Too much air flowing into a space, or not enough air being returned to the system from a space, can raise the air pressure in that space. Rather than flowing through a room from supply duct directly to return duct, air can flow from room to room instead to equalize pressure between rooms with a loss of efficiency in the system overall.

A system can be made more efficient by providing each room within a structure with a return duct. This tends to equalize air pressure throughout the structure and prevents air from migrating from room to room, bypassing the return. Individual room returns can provide nearly 100% recirculation of air back to the air handling system to maximize efficiency.

Two of the biggest problems related to the efficiency of HVAC (heating, ventilation, air conditioning) systems today are lack of maintenance, causing dirty filters, and unbalanced air pressures in different parts of the building. A dirty air filter causes restricted air flow, which in turn causes higher utility bills and a shorter equipment life span due to overheating. The present invention provides easy access for changing the air filter of a forced air heating and air conditioning system located above a ceiling (often in the attic) of a home or building, without actually having to enter the attic to do so.

To compensate for the uneven pressures within some central air systems, some manufacturers, builders and contractors install air return ducts in central locations on a level of a structure (hallways, for instance). However, closed room doors defeat the central return designs by trapping air within a room, raising the internal pressure of that room and restricting return flow to the central air handler. Further aggravating the condition, the central return can also lower air pressure in the rooms with open doors by drawing more air from them to compensate for the air lost to the system in the closed room. Central returns are thus not an effective solution to uneven pressures within a central air handler system.

The present invention provides individual room returns that balance the air pressure within a structure. The air that passes into a room from a supply duct is drawn back to the central unit by the room return duct, through a mixing box, then a filter, and into the air handler.

SUMMARY OF THE INVENTION

An above-ceiling system for conditioning air within a structure comprising a plurality of air return ducts connected to an inlet duct, said plurality of air return ducts representing air returned from each major space in the structure; an inlet duct for mixing the air returned from the plurality of return ducts; a filter housing connected to the inlet duct downstream from the inlet duct through which the returned air passes, said filter housing containing an air filter; an outlet duct connected to the filter housing through which the filtered air passes; and, an air handler and conditioning unit connected to the outlet duct for conditioning the filtered air and supplying the conditioned air to a system of supply ducts. The filter housing and filter are disposed above the ceiling, said filter housing having an opening into the space below the ceiling; and, said opening is closed by a cover secured in place below the ceiling by one or more fasteners such that removal of the fasteners and cover provide access to the filter for removal and replacement from the space below the ceiling.

DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is a schematic drawing of the air handling system of the invention.

FIG. 2 is a perspective drawing of the adjustable filter housing access frame.

FIG. 3 is a perspective drawing of the alternate side of the filter housing access frame of FIG. 2.

FIG. 4 is an overhead plan view of the ceiling above which the system of the invention is installed.

FIG. 5 is a schematic drawing of the filter and housing assembly above the ceiling of FIG. 4.

FIG. 6 is a schematic drawing of the removal and replacement of the filter in the assembly of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

The invention is a central air “conditioning” (intended to encompass heating and/or cooling, and/or humidity control) system for above-ceiling mounting having an adjustable filter access frame that is accessible from below the ceiling without having to physically enter the above-ceiling space. The system also includes individual room air return ducts and connections to the air handler to form a system that provides sufficient air flow to balance pressure among the various rooms of the structure for better efficiency.

Referring to FIG. 1, the main elements of the system are an inlet duct 16 connected to a filter housing 1. The filter housing 1 is connected to a ceiling joist 7 by a joist mounting bracket 4 that is pair of the housing 1. Downstream in the air flow after the filter housing 1 is an outlet duct 17. A flexible duct 20 connects the outlet duct 17 to the main air handler 22, and is connected to each of them by flexible duct connectors 27 a, 27 b. The inlet and outlet ducts, and the air handler and conditioning unit, are mounted to the ceiling joists in the conventional manner (not shown).

With attention to the air flow equalizing aspect of the invention, room air is returned to the air handling system through several individual return ducts 19 (one shown in FIG. 1). Each of the room return ducts 19 is connected to the inlet duct 16 at individual air entries equipped with flexible connectors 18 a-18 e in FIG. 1, which could represent (by way of example only) four bedroom returns and a hall return. Other connections may be provided for more rooms in a structure. The returned air is mixed in the inlet duct 16 and passed through the filter 10 inside the filter housing 1. Post-filtration, the air passes through the outlet duct 17, mixing again as it passes through the outlet duct 17 and the flexible duct 20 on its way to the air handler 22 for conditioning. After conditioning, the conditioned air passes through the supply duct system (not shown) on its way back to the individual rooms of the structure.

With attention now to the filter access aspect of the invention, reference should be made to FIGS. 1-3. The filter housing 1 holds the filter 10 in place after the housing 1 is installed. The components of the system are attached to or formed onto this housing in the described embodiment. The filter 10 fits within a frame 8 that permits the filter to be slid in and out easily for installation and removal.

For proper installation the filter frame height must be adjusted to fit on the joist size in the ceiling above which the system is to be installed such that the bottom of the filter housing is substantially level with an opening in the ceiling that allows access to the filter 10 from below. The frame height is adjusted by disassembling the adjustment nut and bolts 24 a, 24 b which will allow separation of the filter housing 1 and the joist mounting bracket 4. The joist mounting bracket 4 is then placed over the joist mounting bracket height adjustment holes 23 that when lined up properly give you the required depths for mounting on nominal 2×4, 2×6, 2×8, and 2×10 lumber. After the adjustment is complete the joist mounting bracket 4 rests on top of the ceiling joist 7 and is attached to the side of the ceiling joist 7 by means of nails or screws via fastening holes 5. After the joist mounting bracket 4 is attached via the fastening holes 5, support flange 6 is secured on the opposite side of the ceiling joist 7 via fastening holes 28 with nails or screws. Once the joist mounting bracket 4 and the support flange 6 are both secured, the drywall flange 29 protrudes below the bottom of the ceiling joist 7 so drywall 30 can be installed around it.

After the filter housing 1 is secured in place, inlet duct 16 and outlet duct 17 are attached via duct attachment flanges 3 a, 3 b to both sides of the housing 1. After the inlet duct 16 and the outlet duct 17 are attached, small flexible ducts 19 (one shown) from each room requiring a return are attached via flexible duct connectors 18 a-18 e to the inlet duct 16. Thereupon one large flexible duct 20 is attached to the outlet duct 17 via flexible duct connector 27 a. The downstream end of the large flexible duct 20 is then attached to the return side of the air handler 22 via flexible duct connector 27 b.

After the drywall 30 is painted and the system is ready for completion, a filter 10 is inserted into the filter access opening 9 (see FIGS. 4, 6). Then the door 11 is aligned with the filter 10 and pushes it into the filter housing 1 and frame 8. Door 11 is then guided into final position by means of the cover attachment bolts 12 going through the cover attachment bolt holes 13 and decorative knobs 14 are threaded onto the cover attachment bolts 12.

Normally a system located in the attic has a filter that must be changed by either climbing into the attic to get to the filter holder located at the air handler, or changing a filter in a filter/grille mounted flush with the ceiling. Both of these options have their drawbacks. Climbing into the attic requires a ladder, entering the attic and walking across ceiling joists to get to the filter. This is inconvenient at best and potentially dangerous if one steps or falls between joists onto the drywall of the ceiling. Changing a filter in a filter/grille involves opening the grille and changing the filter, but a system with this configuration has only one air return (through the grille) for the entire structure (unless many filter/grilles are distributed through the building, which makes for more filter maintenance). A single air return does not allow proper return air to be directed back to the air handler from all areas needing returns. Also, filter/grilles are often unsightly and dirt always accumulates in them. Because filters should be changed once a month for proper system operation, it is highly desirable that the replacement of the filter be a simple task requiring the least possible difficulty for access, removal and replacement.

In the system described herein, the filter in an above-ceiling system is accessible from below without entering the above-ceiling space. Referring to FIG. 4, what is visible in the ceiling where the system is installed is simply a cover 11 mounted up against the drywall (or other material) ceiling 30. This is a much less disagreeable sight that a filter grille. The cover 11 has knobs 14, desirably decorative in some sense, holding the cover 11 in place over the filter opening 9.

Referring to FIG. 5, the filter 10 is located directly above the cover 11 in the housing 1. The process of removal and replacement is illustrated in FIG. 6. The knobs 14 are removed, allowing the cover 11 to drop from the ceiling. With the cover removed, the filter 10 simply slides out of the frame 8 (not indicated) within the housing 1 and is easily removed. The new filter can be inserted up into the frame, and the cover replaced and secured with the knobs. In most structures with normal 8-9 foot ceiling heights, nothing more than a small stepladder is necessary to perform this task. Entry into the above-ceiling space is unnecessary for this routine maintenance procedure.

The filter and frame may be adapted to receive various sizes of filters required for different conditioning systems. The knob 14 and bolt 12 combination that hold the cover 14 in place can be substituted by fasteners of several varieties without deviating from the function of the invention. The exact structure of the housing 1 and filter frame 8 can vary within the concept of the invention, provided that any variation does not inhibit the accessibility of the filter from below the ceiling level, nor impair the ease with which the filter may be replaced as described above.

Referring back to the system illustrated in FIG. 1, the multiple air returns provided in the system, connected to the inlet duct and mixing box 16 by flexible ducts 19, provide the best possible circulation of conditioned and return air. The return air comes directly from a single space in the structure. Using cooling as the conditioning example, once conditioned air is poured into a space through a supply duct, it displaces air that has been in the space for some time, forcing it into the room return inlet and directly back to the air handling system. That air has not been allowed (or forced) to wander through other spaces in the building, becoming less cool (absorbing heat) on the way. Therefore it is quickly recooled in the conditioning system, returned to the space, and recirculated back for conditioning again. In this way, the system achieves cooling in each space much more efficiently than it would by gulping air from one or two locations in the structure, in effect trying to cool the entire structure at once. For best efficiency, a return duct should be allocated to each and every major space within the structure. For practical reasons, bathrooms, closets and perhaps a basement (unless finished and oft-used) might be excluded.

Even though particular embodiments of the present invention have been illustrated as described herein, it is not intended to limit the invention and changes and modifications may be made therein within the scope of the following claims. 

1. An above-ceiling system for conditioning air within a structure comprising: a plurality of air return ducts connected to an inlet duct, said plurality of air return ducts representing air returned from each major space in the structure; an inlet duct for mixing the air returned from the plurality of return ducts; a filter housing connected to the inlet duct downstream from the inlet duct through which the returned air passes, said filter housing containing an air filter; an outlet duct connected to the filter housing through which the filtered air passes; and, an air handler and conditioning unit connected to the outlet duct for conditioning the filtered air and supplying the conditioned air to a system of supply ducts.
 2. The above-ceiling system for conditioning air of claim 1, wherein: the filter housing and filter are disposed above the ceiling, said filter housing having an opening into the space below the ceiling; and, said opening is closed by a cover secured in place below the ceiling by one or more fasteners such that removal of the fasteners and cover provide access to the filter for removal and replacement from the space below the ceiling.
 3. The above-ceiling system for conditioning air of claim 1, further comprising: a joist mounting bracket on the filter housing, said bracket being adjustable so that its position can be varied to accommodate the size of joist that comprises the ceiling where the system is located, said adjustment locating the opening in the filter housing substantially level with the ceiling surface for access from below.
 4. An above-ceiling system for conditioning air within a structure comprising: a filter housing, said filter housing containing an air filter; the filter housing and filter disposed above the ceiling, said filter housing having an opening into a space below the ceiling; and, said opening is closed by a cover secured in place below the ceiling by one or more fasteners such that removal of the fasteners and cover provide access to the filter for removal and replacement from the space below the ceiling.
 5. The above-ceiling system for conditioning air of claim 4, further comprising: a joist mounting bracket on the filter housing, said bracket being adjustable so that its position can be varied to accommodate the size of joist that comprises the ceiling where the system is located, said adjustment locating the opening in the filter housing substantially level with the ceiling surface for access from below. 